Installation for measuring pressure of at least one aeroplane wheel tyre

ABSTRACT

The invention concerns and installation ( 12 ) for measuring the pressure of at least one tyre of a wheel ( 16, 24 ) of an aeroplane ( 10 ) comprising: at least a pressure measuring sensor ( 26 ) associated with a tyre; a unit ( 30 ) operating on the pressure measurement provided in the aeroplane ( 10 ); and radio-frequency transmission means including for the or each sensor, a revolving antenna ( 28 ) borne by the wheel ( 16, 24 ) and connected to each measuring sensor ( 26 ) and to a fixed antenna ( 34; 134 ) connected by a conductive cable ( 32 ) to the unit operating ( 30 ) on the pressure measurement. The fixed antenna ( 34; 134 ) is adapted to be borne by the aeroplane structure away from the or each wheel ( 16, 24 ) at least in an upper part of the shock strut ( 18, 20, 22 ) of the landing gear ( 14, 20 ) bearing the wheel.

The present invention relates to an installation for measuring thepressure of at least one tyre of an aeroplane wheel, of the typecomprising:

-   -   at least one pressure measuring sensor associated with a tyre;    -   a unit for operating on the pressure measurement provided in the        aeroplane; and    -   radio-frequency transmission means comprising on the one hand,        for the or each sensor, a revolving antenna borne by the wheel        and connected to each measuring sensor and, on the other hand, a        fixed antenna connected by a conductive cable to the unit for        operating on the pressure measurement.

In aircraft it is useful for the cockpit to know the pressure of thetyres on the landing gear wheels.

To this end it is known to mount, on the rim of each wheel, a pressuresensor adapted to measure the inflation pressure of the tyre carried bythe rim.

This pressure sensor sends the measurement to an operating unit providedin the body of the aircraft, and particularly in the cockpit. Thisoperating unit is adapted, for example, to provide the pilot with adisplay on a suitable screen showing the digital value of the pressureof each tyre.

To ensure that the data is transmitted from the sensor to the cockpit itis known to provide data transmission means between the fixed parts andmoving parts of the landing gear.

In particular, it is known to provide, on the hub of the wheel and onthe wheel axle about which the hub is mounted to rotate, two concentriccoils together forming a transformer. The coil borne by the hub isconnected to the pressure sensor while the coil borne by the wheel axleis connected to the data processing unit.

The signal supplied by the sensor to the coil borne by the hub andcorresponding to the level of pressure in the tyre induces a signal inthe coil borne by the wheel axle of the landing gear. This signal isanalysed by the operating unit in order to derive from it the pressurein the tyre and make this available to the crew.

This solution works in a satisfactory manner. However, the presence oftwo concentric coils makes the arrangement relatively bulky.

It has been envisaged to use antennas to provide a radio-frequencytransmission between the moving part of the landing gear and the fixedpart.

In the installations envisaged, an antenna borne by the fixed part ofthe landing gear is disposed on the hub of each wheel facing acorresponding rotary antenna borne by the moving part of the wheel.

The fixed antenna carried by the hub is connected to the unit foroperating on the values, which is situated in the cockpit, by a datatransmission cable.

Thus, the cable passes from the wheel hub along the length of the shockstrut of the landing gear then into the fuselage of the aeroplane.

In large aircraft, the shock strut of each element of the landing gearcomprises two successive sections connected to each other via a shockabsorber.

With the two successive sections rendered movable by the presence of theshock absorber, the passage of the data transmission cable in the regionof the shock absorber is tricky. In particular, the cable is subjectedto repeated mechanical stresses causing accidental breakage of thetransmission cable in this region.

The invention sets out to propose an installation for measuring the tyrepressures of an aircraft which does not have the drawbacks describedabove and which is more reliable.

To this end, the invention relates to an installation for measuring thepressure of at least one tyre of an aeroplane wheel, of the typedescribed above, characterised in that the fixed antenna is adapted tobe borne by the structure of the aeroplane at a spacing from the or eachwheel, at least in an upper part of the shock strut of an element of thelanding gear carrying the wheel.

According to particular embodiments, the installation comprises one ormore of the following features:

-   -   the shock strut has two movable sections connected by a shock        absorber, and the fixed antenna is carried by the upper part of        the shock strut on the movable section which is integral with        the aircraft fuselage;    -   the fixed antenna is carried by the aircraft fuselage;    -   said radio-frequency transmission means are adapted for the        radio-frequency transmission of a power signal for supplying the        or each pressure measuring sensor;    -   it comprises a plurality of sensors associated with a plurality        of movable antennas, and the transmission means comprise means        for discriminating between the signals emitted from each movable        antenna; and    -   the transmission frequency is between 100 kHz and 150 kHz.

The invention also relates to an aeroplane comprising a pressuremeasuring installation as hereinbefore defined.

The invention will be better understood from reading the descriptionthat follows, which is provided solely by way of example and withreference to the drawings, wherein:

FIG. 1 is a diagrammatic view of an aeroplane fitted with aninstallation for measuring the pressure of a tyre according to theinvention;

FIG. 2 is a diagrammatic view of the installation for measuring thepressure in two separate tyres of the same landing gear of an aeroplane;and

FIG. 3 is a diagrammatic view of an element of the landing gear of anaeroplane on which is mounted an alternative embodiment of a pressuremeasuring installation according to the invention.

The aeroplane 10 shown in FIG. 1 is fitted with an installation 12 formeasuring the pressure of each of the tyres of the aeroplane wheels. Asknown per se, the aeroplane has at the front a landing gear element 14comprising a number of wheels 16 arranged at the free end of a shockstrut 18. Similarly the aeroplane comprises, underneath each wing, alanding gear element 20 comprising a shock strut 22 at the end of whichare mounted a number of wheels 24.

Each shock strut 18, 22 of the landing gear elements 14, 20 comprisestwo successive sections which are movable relative to one another andjoined together by a shock absorber.

Each tyre fitted to a wheel 16, 24 of the aeroplane is associated with apressure sensor generally designated 26.

As known per se, the pressure sensor is borne for example by the rim ofthe wheel.

Each pressure sensor 26 is connected to a rotary antenna generallydesignated 28. This antenna 28 is fixedly attached to the rim and ismounted to rotate with the wheel relative to the shock strut of thelanding gear element carrying the wheel.

Inside the aeroplane and especially in the cockpit there is a unit 30for operating on the pressure measurement in each tyre of the aeroplane.This operating unit 30 comprises, for example, a set of displaysinforming the pilot of the pressure level in each tyre.

This operating unit 30 is connected by a data transmission cable 32 to afixed antenna 34 adapted to receive and transmit data from and to theantennas 28 associated with each sensor 26 mounted on the wheels of theaeroplane.

According to the invention, the fixed antenna 34 is carried by thestructure of the aeroplane, at a spacing from each wheel, at least inthe upper part of the shock strut of each landing gear element carryinga wheel.

More precisely, in the embodiment in FIG. 1, the fixed antenna 34 isfixed under the fuselage of the aircraft, in the front region thereof,close to the aircraft cockpit.

FIG. 2 shows the electronic structure of the radio-frequency datatransmission means which permit communication between each of thepressure sensors and the operating unit 30. These transmission means aregenerally designated 38.

In this Figure, only two sensors 26 and their associated movable antenna28 are shown.

Each sensor 26 comprises a transducer 40 adapted to convert the pressureinside the tyre into an electric signal. In addition, the sensor 26comprises a data processing unit 42 comprising computing means 44 andcoding and decoding means 46.

The processing unit 42 is connected to a transmitting/receiving unit 48to which the movable antenna 28 is connected.

The transmitting/receiving unit 48 comprises a demodulation stage 50adapted to produce, from the radio-frequency signal received by theantenna 28, on the one hand a data signal 52 addressed to the coding anddecoding means 46 and, on the other hand, a power signal 54 whichsupplies the data processing unit 42 on the one hand and all the stagesof the transmitting/receiving unit 48.

The electric power sent by the demodulation stage 50 comes from theradio-frequency signal received. This radio-frequency signal is thusadapted for power transmission. It has, for example, a frequency ofbetween 100 kHz and 150 kHz. This frequency is preferably 125 kHz.

The coding and decoding means 46 are adapted to interpret a pressuremeasurement command received from the cockpit through theradio-frequency communication.

In addition, the coding and decoding means 46 are adapted to code apressure value produced by the processing means 44 for reading thetransducer 40. This coding is carried out in particular in order to addto the pressure value, in the coded message, an identifier for thesensor 26, so that the pressure measurement value can be associated witha tyre.

Moreover, the transmitting/receiving unit 48 comprises a modulatingstage 56 for the signal, which is adapted to convert the coded messagecoming from the coding and decoding means 46 into a signal suitable forradio-frequency transmission from the antenna 28. The modulation stage56 is connected for this purpose to the antenna 28 in order to send themodulated signal to the fixed antenna 34.

The antenna 34 is connected, like each antenna 28, to atransmitting/receiving unit 60. The latter is connected to a dataprocessing unit 62, which is in turn connected to the unit operating onthe values 30. This operating unit consists of a display, for example.

In addition, the transmitting/receiving unit 60, the data processingunit 62 and the operating unit 30 are all supplied by an electricalenergy source 64. This supply is provided for example through theaeroplane's own power distribution network.

The transmitting/receiving unit 60 comprises a demodulation stage 66which makes it possible to receive the modulated signal coming from theantenna 34 and to form from it a digital baseband signal which can beutilised by the data processing unit 62.

Similarly, the communication unit 60 comprises a modulation stage 68adapted to shape a signal coming from the data processing unit 62. Inaddition, this modulation stage 68 is adapted to combine, in a modulatedsignal, the data coming from the data processing unit 62 and a powersignal for supplying the measuring sensors associated with the tyres.

The data processing unit 62 comprises coding and decoding means 70 foridentifying, in the signal coming from the demodulating means 66, theorigin of the pressure measurements as a function of the code providedby the pressure sensor which has sent the information. Moreover, thecoding and decoding means 70 effect the coding of the pressure requestssent to the modulating module 68 so that the request will be recognisedby only one of the sensors.

The data processing unit 62 also comprises processing means 72 forshaping the pressure measurements received so that they can subsequentlybe processed by the operating means 30.

In order to obtain a pressure measurement, the data processing unit 62generates a request with a code appropriate to the sensor for the tyrewhose pressure is to be recorded. This coded signal is modulated by themodulating stage 68.

Each of the sensors 26 receives the signal emitted by the antenna 34.The demodulation stage 50 of each sensor 26 carries out the demodulationof the signal, which is then sent to the data processing unit 42 andparticularly to the coding and decoding means 46. If the requestreceived contains a code which is recognised by the processing unit 42,the pressure measurement value returned by the transducer is shaped bythe processing means 42 and encoded by the unit 46 before beingmodulated by the stage 56 for transmission. After this, the signal thusmodulated is sent from the antenna 28 to the antenna 34.

If the sensor 26 does not recognise the request sent to it, it does notsend any data back to the antenna 34.

The signal received by the antenna 34 is demodulated by the demodulationstage 66, then sent to the coding and decoding means 70, which identifythe sensor that has carried out the pressure measurement. Thanks to theprocessing means 72, the pressure value is made available to the pilotsof the aircraft by being displayed on the means 30 which operate on thepressure measurement value.

FIG. 3 shows an alternative embodiment of the installation according tothe invention.

In this embodiment, the fixed antenna designated 134, which is analogousto the fixed antenna 34, is located on the upper part of the shock strut122 of the landing gear element. In particular, it is borne by thesection 122A which is fixedly attached to the aircraft fuselage.

As before, each tyre is associated with a pressure sensor 26 connectedto a movable antenna 28.

In this embodiment, as in the previous one, a radio-frequencytransmission is established between the rotating antenna 28 on eachwheel and the fixed antenna 134. This radio-frequency transmissionensures both transmission of data and transmission of energy to supplythe sensors.

The shock strut 122 comprises two successive sections 122A, 122Bconnected by a shock-absorbing element 122C.

In the embodiments in FIGS. 1 and 3, the movable antennas 28 and fixedantennas 34 or 134 are mounted at a spacing from one another, andparticularly on either side of the shock absorbing element of thelanding gear. Thus, it will be seen that there are no wires runningalong the length of the shock absorber, thus reducing the risk of thecable breaking.

1. Installation (12) for measuring the pressure of at least one tyre ofa wheel (16, 24) of an aeroplane (10), comprising: at least one pressuremeasuring sensor (26) associated with a tyre; a unit (30) operating onthe pressure measurement, provided in the aeroplane (10); andradio-frequency transmission means comprising on the one hand, for theor each sensor, a revolving antenna (28) borne by the wheel (16, 24) andconnected to each measuring sensor (26) and, on the other hand, a fixedantenna (34; 134) connected by a conductive cable (32) to the unit (30)operating on the pressure measurement, characterized in that the fixedantenna (34; 134) is adapted to be carried by the structure of theaeroplane at a spacing from the or each wheel (16, 24) at least in anupper part of the shock strut (18, 20; 122) of a landing gear element(14, 20) carrying the wheel.
 2. Measuring installation according toclaim 1, characterized in that the sock strut (18, 20; 122) has twomovable sections (122A, 122B) connected by a shock absorber (122 c), andthe fixed antenna (134) is carried by the upper part (122 a) of theshock strut (122) on the movable section (122A) which is integral withthe aircraft fuselage.
 3. Measuring installation according to claim 1characterized in that the fixed antenna (34) is carried by the aircraftfuselage.
 4. Installation according to claim 1, characterized in thatsaid radio-frequency transmission means are adapted for theradio-frequencey transmission of a power signal for supplying the oreach pressure measuring sensor (26).
 5. Installation according to claim1, characterized in that it comprises a plurality of sensors (26)associated with a plurality of movable antennas (28), and in that thetransmission means comprise means for discriminating between the signalsemitted from each movable antenna (28).
 6. Installation according toclaim 1, characterized in that the transmission frequency is between 100kHz.
 7. Aeroplane comprising an installation for measuring the pressureof at least one tyre of a wheel according to claim 1.